25 April 2008

Dengue activity update

Increased dengue activity is currently being reported throughout endemic areas of the world. Dengue is endemic in many tropical countries, including South East Asia, the Indian subcontinent, the Caribbean, South and Central America, northern Australia and the islands of the South Pacific. Outbreaks are most frequent following heavy rains when there is increased mosquito activity.  

Dengue is a mosquito-borne virus of the Flaviviridae family. There are four serotypes of dengue virus classified as DEN 1 to 4. The virus is transmitted via the bite of an infected Y mosquito; Y is the principle vector, but A. albopictus has also been responsible for transmission of dengue in some countries. Dengue is recognised in more than 100 countries and between 250,000 to 500,000 cases are reported to the World Health Organization annually.

The majority of cases of dengue are sub-clinical or mild. Following an incubation period of five to eight days, a fever develops which lasts from one to five days. Other symptoms include headache, myalgia, and cough. A maculopapular rash typically spreading from the trunk to the limbs and face develops between three and five days after onset of the illness. Most patients will make a rapid recovery three to four days after onset of the rash.

Dengue can progress to the more serious dengue haemorrhagic fever (DHF). This is more common in children and rarely seen in travellers. Previous infection with a different serotype of dengue may predispose to DHF on re-infection. During DHF there is a sudden deterioration with diffuse bleeding and shock, leading to organ failure.

There is no specific treatment for dengue or DHF. Supportive care and management of symptoms are the standard. 

Advice for travellers

There is no vaccine available to protect against dengue. Travellers to endemic areas can reduce their risk of infection by the dengue virus by practising mosquito bite avoidance measures. Aedes mosquitoes responsible for transmitting dengue are active during daylight hours. Particular vigilance with bite avoidance should be taken around dawn and dusk.

Links

NaTHNaC Health Information Sheet on Dengue

Centers for Disease Control and Prevention. Outbreak notice: Dengue, tropical and sub-tropical regions. April 16, 2008 available at http://wwwn.cdc.gov/travel/contentDengueTropicalSub

Tropical.aspx

NaTHNaC News: Dengue in Brazil, 7 April 2008

NaTHNaC News: Dengue fever activity, 23 February 2007